When in battle, you can find an action meter at the bottom of the screen. Each hero avatar represents 1 Turn of the hero.
When all heroes have finished their turns and the Round icon moves from the very left to the very right, it means a round has ended.
Example
[Round Begins]
[Round Ends]
When all heroes have finished their turns and the Round icon moves from the very left to the very right, it means a round has ended.
Example
[Round Begins]
[Round Ends]
